Method of increasing propellant burning rate by the use of high conductive wires

ABSTRACT

4. A solid propellant composition which comprises a cured intimate mixture of a solid non-metallic oxidizing salt and a cross-linked resin binder which comprises the reaction product of a compound having, as its sole reacting groups, not less than two active hydrogen groups capable of polymerizing with an isocyanate as determined by the Zerewitinoff method, and a compound having, as its sole reacting groups, not less than two groups capable of undergoing a urethane-type reaction with hydroxy groups and as a burning rate additive, elongated metallic staples having a heat conductivity of from about 0.10 to about 1.05 gram-cal/(sec) (sq.cm.) (*C/cm) and a melting point above about 600*C, in an amount effective to increase the burning rate up to an amount not greater than that equivalent to about 15 percent by weight of the propellant composition.

United States Patent [1 1 Lawrence METHOD OF INCREASING PROIELLANTBURNING RATE BY THE USEOF HIGH CONDUCTIVE WIRES Ralph W. Lawrence,Glendora, Calif,

Assignee: Aerojet-General Corporation,

Azusa, Calif.

Filed: Jan. 17, 1964 Appl. No.: 338,527

Inventor:

References Cited UNITED STATES PATENTS 1l/1963 Rumbel et al. 149/29/1964 Afere et al 149/19 12/1964 Davis et a1. 102/102 [451 Feb. 19,1974 Primary ExaminerBenjamin R. Padgett EXEMPLARX CLAIM 4. A solidpropellant composition which comprises a cured intimate mixture of asolid non-metallic oxidizing salt and a cross-linked resin binder whichcomprises the reaction product of a compound having, as its solereacting groups, not less than two active hydrogen groups capable ofpolymerizing with an isocya nate as determined by the Zerewitinoffmethod, and a compound having, as its sole reacting groups, not lessthan two groups capable of undergoing a urethanetype reaction withhydroxy groups and as a burning rate additive, elongated metallicstaples having a heat conductivity of from about 0.10 to about 1.05gramcal/(sec) (sq.cm.) (C/cm) and a melting point above about 600C, inan amount effective to increase the burning rate up to an amount notgreater than that equivalent to about 15 percent by weight of thepropellant composition.

17 Claims, No Drawings METHOD OF INCREASING PROPELLANT BURNING RATE BYTHE USE OF HIGH CONDUCTIVE WIRES This invention pertains to a novelrapid burning solid propellant composition and to the method for itspreparation. v

Solid propellant rocket motors have been previously employed intactical, intermediate range and intercontinental ballistic missies. Forthese applications the propellant normally need only be of moderateburning rate since ample time is provided for the production of thenecessary thrust. However, it has now become necessary to provide asolid propellant rocket motor for use in the interception of incomingballistic missle nuclear warheads. To be successful, such an antimissilemissile must be capable of rising very rapidly from the ground uponreceiving directions from a computer and proceed to the point ofinterception which must be far enough from the ground so that theincoming warhead may be destroyed by nuclear explosives withoutendangering the underlying land mass. In order that this may beaccomplished, the solid propellant employed in the antimissile missilemust be capable of producing a large thrust very quickly. T provide thishigh acceleration, the propellant must possess a high burning rate.

It is therefore an object of this invention to prepare a novelpropellant which possesses a sufficiently high burning rate to besuitable in an antimissile missile. Specifically, it is an object ofthis invention to prepare a solid rocket propellant which has a burningrate 300 to 500 percent of that obtainable with ordinary solid rocketpropellants. These and other objects of this invention will be apparentfrom the detailed description which follows.

It has now been found that a solid propellant composition of highburning rate may be obtained by incorporating therein metallic staplesin an effective amount, normally from about 1 percent to about 15percent by weight of the total propellant composition. The staples ofthis invention are of long and narrow dimensions, that is, elongated.The staples may be of any crosssectional shape but normally they arerectangular,-

square or circular in cross-section.

The metallic staples which are employed as burning rate additives in thepropellants of this invention are comprised of any metals or metalalloys of high heat conductivity [from about 0.10 to about 1.05gramcal./(sec.)(sq.cm.)(C/cm.)]' and high melting point (above about600C) such as copper, aluminum, iron, stainless steel, hafnium, brass,zirconium, copperaluminum alloy, aluminum coated nickel, nickel coatedaluminum and palladium coated aluminum. These c'oated staples areprepared by electrolytic techniques known to those skilled in the art.When the metallic staples are circular in cross-section, they may varyin diameter from about 2.0 to about 10 mils, and in length from about 50to about 500 mils. Preferably, such needle-like materials have a lengthof from about 250 mils to about 375 mils. The staples of my inventionhaving a square cross-section preferably measure from about 0.5 to about10 mils on a side and are from about 50 to about 500 mils in length. Thestaples of rectangalar cross-section measure from 0.4 to about 5.0 milson the short side and from about 1.0 to about 20 mils on the long sideand are from about 50 to about 500 mils in length. These metallicstaples may be incorporated into the propellant any time during theprocessing operation prior to the casting and curing steps.

When the staples are used according to the practice of this invention,the burning rate is increased above 5 that obtained by addition of knownburning catalysts. Further, the staples of this invention provideincreased burning rate without adversely affecting the specific impulseof the propellant. However, it is contemplated that where even higherburning rates are required, conventional burning rate catalysts such ascopper chromite, in amounts from about 0.1 to about 2 percent by weightof total propellant, can be used in conjunction with the metallicstaples.

As the primary propulsion source for an antimissile missile, propellantsof this, invention can be conveniently ignited by a conventionaligniter, as for example, the igniter disclosed in Assignees US. Pat. No.3,000,312, issued Sept. 19, 1961. The rocket chambers in which the novelsolid propellants are employed are ordinarily of a conventional typehaving one open end which leads to a venturi nozzle. Upon ignition,large volumes of gases are produced and exhausted through the nozzle tocreate thrust.

A preferred class of binders for use in the rapid buming propellants ofthe present invention are the reaction products of a carboxy-terminatedpolydiolefin of the formula:

2 Z l... l N

i H v "A 1 13 3 wherein Z is oxygen or sulfur; and R and R are hydrogenor lower alkyl such as methyl, ethyl and pentyl;

wherein R is a trivalent organic radical of the formula:

and R and R is hydrogen or lower alkyl of from 1 to about 4 carbons; and

Ii R wherein A is alkylene, preferably lower alkylene of from one toabout 12 carbons, and R R R and R are hydrogen or lower alkyl of fromone to about four carbons. Normally, the-aziridinyl curing agent isemployed in an amount from 1 to about 40 parts per 100 parts of thefunctionally-terminated polydiolefin. The preferred polydiolefin of theabove formula is polybutadiene or polyisoprene having a molecular weightof from about 400 to about 5,000, a viscosity at 77F of from about 5 toabout 500 poise, and is carboxyterminated (Y COOH).

Typical aziridinyl curing agents within the scope of the foregoingformulae include: tris( N-l ,2'-butylene)trimesamide, tri(2-methyl-3-n-butyll -aziridinyl)phosphine oxide, tri(2-ethyl-3-octadecyll -aziridinyl )phosphine oxide, tri(2-methyl-3-cyclopentyll -aziridinyl)phosphine oxide, tri(2-methyl-3-benzyll -aziridinyl )phosphine oxide, tri(l-aziridinyl)phosphine sulfide, tri( Z-methyll -aziridinyl )phosphinesulfide, tri(Z-eicosyl-l-aziridinyl)phosphine sulfide, and tri(2-methyl-3-cyclohexyll-aziridinyl)phosphine sulfide.

The polyurethane binders which can be used in my propellants areprepared by reacting a compound having two or more active hydrogencontaining groups capable of polymerizing with an isocyanate asdetermined by the Zerewitinoff method, with an organic compound havingas the sole reacting groups, two or more isocyanate or isothiocyanategroups. The active hydrogen containing groups are preferably hydroxy orthiol.

it will be apparent that, where more than two active hydrogen,isocyanate, or isothiocyanate groups are present in any of thepolyurethane reactants, the structure of the polyurethane binder willcontain at least some cross-linking. Where bifunctional reactants, suchas dihydroxy compounds and diisocyanates are employed to produce thepolyurethane binders for our novel propellants, it is necessary to alsoemploy a cross-linking agent to provide a product having a cross-linkedstructure. Compounds suitable as crosslinking agents for thepolyurethane binders are those compounds having as the sole reactinggroups at least three groups polymerizable with active hydrogen orisocyanate groups.

Examples of compounds which we have found to be particularly suitable ascross-linking agents are 1,2,6- hexanetriol; methylenebis-(orthochloroaniline); monohydroxyethyl trihydroxypropylethylenediamine; N,N,N',N'-tetrakis (Z-hydroxypropyl) ethylenediamine;triethanolamine; and trimethylolpropane.

A wide variety of polyurethane binders for the propellants of thisinvention can be prepared by varying the starting materials. Thesepolyurethane binders are disclosed in greater detail in Assigneesco-pending patent applications Ser. No. 829,180 and Ser. No. 829,182,both filed July 23, 1959.

The preferred diisocyanate compounds are saturated or unsaturated;aliphatic or aromatic; open or closed chain; and substituted or not bygroups substantially unreactive with isocyanate or hydroxyl groups suchas ketone or ether groups. Diisocyanate compounds such as tetramethylenediisocyanate, decamethylene diisocyanate; m-phenylene diisocyanate;diphenylene-4,4- diisocyanate; 2,4-tolylene diisocyanate; 3-nitraza-l,3-pentane diisocyanate; duren diisocyanate; and 2,6- tolylene diisocyanateare particularly suitable as reactants for the preparation ofpolyurethane binders.

The preferred hydroxy starting materials for the polyurethane bindersare dihydroxy compounds having the general formula:

where R is a divalent organic radical, such as alkylene or arylene. Thehydroxy groups on the above compounds can be of any type suitable forthe urethane reaction with isocyanate groups such as, for example,alcohol or phenolic hydroxy groups.

Other dihydroxy compounds suitable for the polyurethane reaction of thisinvention are polyesters such as those obtained from the reaction of adihydric alcohol such as ethylene glycol, with a dicarboxylic acid suchas succinic acid. The polyesters most suitable for purposes of thisinvention are those having a molecular weight from about 1,000 to about2,500.

In addition to the polyesters, polyethers such as polyethylene etherglycols, polypropylene ether glycols, other polyalkylene ether glycols,and mixtures or copolymers thereof having molecular weights of fromabout 400 to about 10,000 can be utilized as dihydroxy reactants of thepolyurethane reaction of this invention.

Other binders which may be employed in my novel propellants includeresinous binders such as rubbers, polysulfides, and rubber-polysulfidemixtures.

Examples of rubber binders which can be employed within the scope ofthis invention are polyisobutylene, butyl rubber, butadiene-styrenecopolymers such as Buna-S, a butadiene-acrylonitrile copolymer such asBuna-N, highly polymerized vinyl alcohols in a plasticized state such aspolyvinyl alcohol and pol-ychloroprene. The polysulfides suitable assolid propellant binders are exemplified by polyalkylene sulfides suchas that resulting from the condensation of ethylene dichloride andsodium tetrasulfide. A more complete description of rubber andpolysulfide propellant binders can be found in Assignees US. Pat. No.3,012,866, issued Dec. 12, 1961.

Still other examples of polymeric organic material suitable as bindersare phenol-aldehyde resins, polyester resins, acrylate resins andpolyalkylene resins.

The so-called polyester resins suitable for use as propellant bindersare fonned by reacting a polyhydric alcohol with a polycarboxylic acidand copolymerizing therewith a monomeric ethylenically unsaturatedcompound, compatible with the resin. To permit heteropolymerizationbetween the polyester and ethylenically unsaturated components, thepolyesters are provided with some unsaturation through the incorporationtherein of unsaturated polycarboxylic acid or an hydride and/orunsaturated polyhydric alcohol.

Saturated polycarboxylic acids useful in compounding the polyesterresins are, for example, the aliphatic dibasic acids, including oxalic,malonic, succinic, glutaric, adipic, pimelic, sebacic and azelic. Theunsaturated acids useful as the acidic components in forming polyesterresins are maleic acid, fumaric acid, citraconic acid and mesaconicacid, itaconic acid. The anhydrides such as itaconic anhydrides andphthalic anhydride may also be used to supply the desired unsaturation.

Regardless of which of the saturated acids are used, the degree ofunsaturation necessary to provide crosslinkage with the ethylenicallyunsaturated components may be obtained by the addition of any of theabovenamed unsaturated acids or their anhydrides.

The alcohols that can be used are not limited to the dihydric alcoholsas other polyhydric alcohols such as the trihydric and higher polyhydricalcohols may be used. For the polyhydric alcohol component any of thefollowing alcohols may be used: dihydric alcohols such as ethyleneglycol, diethylene glycol, triethylene glycol and propylene glycol; atrihydric alcohol such as glycerol; tetrahydric alcohols such as theerythrilols and pentaerythritols; pentitols which include arabitol,adonitol and xylitol; hexatols including mannitol; sorbitol anddulcitol; heptitols such as persitol and volamitol; or mixtures of anyof the above alcohols may be also employed if desired.

The ethylenically unsaturated component of the polyester resin bindersmay be styrene, vinyl acetate, methyl methacrylate, allyl diglycolcarbonate, diallyl maleate, diallyl glycolate, propylene, butadiene,etc.; as well as derivatives of any of the above substances which arecapable of polymerization with the polyester resin.

The polyester resins suitable as propellant binders and their methods ofpreparation are more fully disclosed in Assignees U.S. Pat. No.3,031,288, issued Apr. 24, 1962.

Acrylate resin binders within the scope of this invention comprise.copolymers of any two or more reduced oxygen-containing polymerizablemonomers such as alkenoic acids, alkenoic acid esters, dialkenyldiglycolates, dialkylene diglycol bis-(alkenyl carbonate), alkenylphthalates,. etc. Examples of reduced oxygencontaining polymerizablemonomers suitable for acrylate propellant binder formation are theacrylates and methacrylates such as methyl methacrylate, methylacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butylmethacrylate, propyl methacrylate, diethylene glycol bis-(allylcarbonate), diallyl phthalate, diallyl diglycolate, diallyl maleate anddiallyl fumarate.

Other acrylate binders suitable for use in my invention are prepared bycopolymerizing polymerizable substances containing unreducedoxygen inthe molecule, such as the nitro and nitroether-substituted alkenoicacids and esters. Specific examples of nitrocontaining monomers whichcopolymerize to form acrylate propellant binders are 2-nitroethylacrylate; the nitrobutyl acrylates; 2,2-dinitropropyl acrylate;2,2,3,3-tetranitrobutyl acrylate and 2,2,3,3- tetranitrobutylmethacrylate.

Still other acrylate binders comprise copolymers of any one or more ofthe above-mentioned reduced oxygen-containing monomers and any one ormore of the above-mentioned monomers containing unreduced oxygen in themolecule. These binders, as well as those acrylate binders referred toabove, and their methods of preparation are more fully described inAssignees copending U.S. Pat. application Ser. No. 321,941, filed Nov.21, 1952, and now abandoned.

Polyurethane resins containing unreduced oxygen are suitable binders forthe propellants of my invention. Such binders can be prepared bycondensing nitrocontaining isocyanates and nitro-containing alcohols, asmore fully disclosed in Assignee's copending U.S. Pat. application, Ser.No. 728,491, filed Apr. 14, 1958.

' novel solid propellant composition are nitrocelluloseplasticizerbinders of the type prepared by curing mixtures of finely dividednitrocellulose and suitable plasticizers such as pentaerythritoltrinitrate. Binders of this type and their methods of preparation arewell-known to those skilled in the propellant art.

A finely divided nitrocellulose suitable for use in the preparation ofthe subject binders is obtained by first dissolving nitrocellulose,preferably prepared from cotton linters, in a solvent such as an ethylacetatemixture, an ethyl acetate-ethanol mixture, or nitromethane toform a lacquer. The lacquer is slurried in an aqueous medium containinga suspending agent such as methyl cellulose in combination with anemulsifier such as turkey red oil and an agent to prevent agglomerationsuch as, for example, sodium chloride as a result of which thenitrocellulose precipitates from the solvent and is recovered as aparticulate material having an average particle size of 10 to 12 micronsand an over-all particle size rangeof from about 1 to about 35 microns.Finely divided nitrocellulose prepared by the above-described method isknown to those skilled in the art as plastisol grade nitrocellulose andwill be hereinafter referred to as such. Plastisol grade nitrocelluloseis readily available on the open market.

The propellants of this invention contain, as oxidizers, oxidizing saltssuch as the chromates, dichromates, permanganates, nitrates, chloratesand perchlorates of ammonia, hydrazine, quanidine, etc. The selection ofthe oxidizing salt depends upon the specific burning properties desiredin the propellant grain. Mixtures of suitable inorganic oxidizing saltscan be used within the scope of this invention. The propellants may alsocontain from 1 to about 20 percent by weight of the'propellant ofpowdered metal fuels such as powdered aluminum.

Various additives may be employed in preparing the binders of thisinvention. For example, plasticizers, such as, isodecyl pelargonate,polybutene, dioctyl azelate, bis-(2,2-dinitropropyl) formal andbis-(2,2- dinitropropyl) acetal may be utilized. Also, catalysts such asferric acetylacetonate and boron trifluoride can be employed if desired.The catalysts can be employed in quantities within the range from meretraces up to amounts equivalent to about one percent by weight of thetotal propellant composition. Normally amounts of Because highertemperatures tend to produce shrinkage and internal strains, it ispreferable to carry out the cure at temperatures in the range of fromabout 70 to about 180F. Within this range the reaction rate issufficiently rapid for economical production. Yet the temperature is notso high as to produce shrinkage and internal stresses which must beavoided at all costs especially in the case of large solid propellantmotors.

Those skilled in the art will appreciate the fact that heating andcooling steps can be incorporated into the propellant processingprocedure to attain optimum operating conditions for producing a givenspecific propellant. Likewise, various techniques which may serve tooptimize the processing procedure or improve the quality of the product,e.g. vacuumizing the mixture during certain phases of the operation, canbe employed if desired. The various processing steps can be carried outwith standard equipment well-known to those skilled in the art. Themixer can be equipped with facilities for heating, cooling, andvacuumizing propellant batches during mixing.

There are many ways of processing the various ingredients within thescope of this invention in the formulation of propellants therefrom, andthese procedures may be readily determined by those skilled in the art,depending on the precise binder, oxidizer, plasticizer, etc., selectedand size of the batch to be prepared.

As noted above, from about 1 to about 15 percent by weight (totalpropellant weight basis), of the metallic staple are employed forpurposes of this invention. The propellant binder is preferably employedin a proportion within the range from about 5 to about 55 percent andthe inorganic oxidizing salt in an amount within the range from about 95to about 45 percent by weight.

The following examples are included for purposes of illustrating thenovel process and propellant composition of this invention. Theseexamples are intended for illustration purposes only and should not beconstrued as limitative of the scope of the invention to the particularconditions and embodiments set forth therein.

EXAMPLE I INGREDIENT WEIGHT PERCENT Ammonium perchlorate 81.50 Powderedaluminum 1.00 lsodecyl pelargonate 3.50 Lecithin 0.24 Aluminum staple(0.5X4.0 62 mil) 4.00 Copper chromite 1.50 Carboxy terminatedpolybutadiene 7.40 Tris-(Z-methyl aziridinyhphosphine oxide 0.86

To a mixer maintained at about 140F was added the carboxy-terminatedpolybutadiene and the powdered aluminum. Then the ammonium perchloratewas slowly added while maintaining the temperature at about 140F. Theisodecyl pelargonate, lecithin and copper chromite were then added. Themixer was subjected to vacuum of 28 inches Hg for 20 minutes whileadjusting the temperature to about 150F. The temperature was thengradually reduced to about 125F while maintaining the vacuum. Thealuminum staple was then added in three equal incremens whilemaintaining the temperature at F. The mixer was then scraped down, andthe tris (2-methyl aziridinyl) phosphine oxide was then added. The mixerwas then vacuumized for 5 minutes at 125F and then scraped down. Thevacuum was again applied for 5 minutes at 125F. The propellant was thencast into motor casings and cured at about F for three days.

EXAMPLE Il Following the procedure of Example 1, the following threepropellants, all of equal solids loading, were prepared. ln PropellantA, no metal staple was used; in Propellant B, 3 percent staple; and inPropellant C, 5 percent staple.

The burning rates of Propellants A, B and C are listed in Table I.

TABLE I Propellant Burning Rate (inches/sec.)

A 1.00 B 3.70 C 3.90

As can be seen from the foregoing data, the incorporation of the metalstaples substantially increases the burning rate of the propellant.

In a preferred embodiment of this invention, the metallic staples priorto incorporation in the propellant are coated with a pyrotectivemixture. The pyrotective coating mixture can consist of a mixture ofiron and potassium permanganate or of aluminum and potassiumperchlorate. The mixed powders are made to adhere to the needles bymixing the powders with a resin such as lacquer, to which a volatilethinner has been added.

One method of preparing coated needles for use in the rapid burningpropellants of this invention is set forth in the following example.

EXAMPLE III A Slurry of powdered iron (32 percent), powdered potassiumpermanaganate (52 percent) and lacquer (16 percent) diluted with benzenewas prepared. Aluminum wire having a diameter of 8 mils is then passedthrough the slurry and wound on a reel at such a distance that thesolvent has evaporated. The wires are then cut into needles varying inlength from 250 to 375 mils.

EXAMPLE IV INGREDIENT WEIGHT PERCENT NH,NO; 65.50 (HN,),Cr O-, 1.80Polyester from 7 moles of adipic acid, 3 moles 8.80 of maleic anhydrideand l 1 moles of diethylene glycol Styrene 2.22 Methyl acrylate l 1.00Lecithin 0.03 Methylethyl ketone peroxide 0.45 t-Butyl catechol 0.20Aluminum wire 250 mils (prepared as in 10.00 Example 111) EXAMPLE VINGREDIENT WEIGHT PERCENT NH,NO 69.30 (NH,) Cr,O-, [.90 Polyester from 7moles of adipic acid, 3 moles 9:30 of maleic anhydride and l 1 moles ofdiethylene glycol Styrene 2.37 Methyl acrylate l 1.60 Lecithin 0.03Methyl ethyl ketone peroxide 0.47 t-Butyl catechol 0.23 Aluminum wire250 mils (prepared as in Example III) 4.80

EXAMPLE VI INGREDIENT WEIGHT PERCENT The aluminum staple is stirred intoabout one-third of the required volume of polypropylene glycol andglycerol mono-ricinoleate. The mixture is prepared in a stainless steelcontainer. Mixing is continued for about 10 minutes. The aluminum stapleslurry is added to a conventional mixture equipped with facilities forheating, cooling and vacuumizing the propellant mix. The walls of thealuminum staple slurry container are scraped thoroughly. The containeris rinsed with the dioctyl azelate and the rinses are added to themixture. The remaining polypropylene glycol is added to the mixer.

With the mixer. off, the ferric acetylacetonate, phenylbetanaphthylamine and lecithin are added. The mixer is convered andmixed for about minutes under 26 to 28 inches of vacuum, after which itis stopped and vacuum released. The oxidizer is then added, with themixer blades in motion. After all of the oxidizer has been added, themixer is stopped and scraped down. The propellant mass is mixed for 15minutes at 70F under 26 inches vacuum. The mixer is stopped and thevacuum released. The tolylene diisocyanate is added, after which themass is mixed for 10 minutes at 70F and 26 inches or vacuum. The vacuumis then released and the mixture is cast.

The following are other propellant formulations from which propellantgrains are prepared according to methods similar to that described inthe foregoing example.

EXAMPLE VIII INGREDIENT WEIGHT PERCENT Ammonium perchlorate 81 .50Stainless steel staple (0.5 4.0X'125-mil) 2.00 Polypropylene glycol 9.63Glycerol monoricinoleate 1.18 Dioctyl azelate 3.12 Ferricacetylacetonate 0.04 Phenyl betanaphthylamine 0.20 Lecithin 0.21 Copperchromite 0.50 Hexamethylene diisocyanate 1.62

EXAMPLE IX INGREDIENT WEIGHT PERCENT Ammonium perchlorate 81.50 Brassstaple (0.5 (4.0X250 mil) 2.00 Polypropylene glycol 9.63 Glycerolmonoricinoleate 1.18 Dioctyl azelate 3.62 Ferric acetylacetonate 0.04Phenyl betanaphthylamine 0.20 Lecithin 0.21 Tolylene diisocyanate 1.62

EXAMPLE X INGREDIENT WEIGHT PERCENT Ammonium perchlorate 81.50 Zirconiumstaple (0.5X4.0X62 mil) 2.00 Polypropylene glycol 9.63 Glycerolmonoricinoleate 1.18 Dioctyl azelate 3. 12 Ferric Acetylacetonate 0.04Phenyl betanaphthylamine 0.20 Lecithin 0.21 Copper chromite 0.50Tolylene diisocyanate 1.62

EXAMPLE XI INGREDIENT WEIGHT PERCENT Hydrazine perchlorate 81 .50 Ironstaple (1.0X4.0X mil) 2.50 Polypropylene glycol 9.63 Glycerolmonoricinoleate 1.18 Dioctyl azelate 3.12 Ferric acetylacetonate 0.04Phenyl betanaphthylamine 0.20 Lecithin 0.21 Tolylene diisocyanate 1.62

EXAMPLE XII INGREDIENT WEIGHT PERCENT Ammonium perchlorate 81.50 Hafniumstaple (1.0X5.0 200 mil) 2.00 Polypropylene glycol 9.63 Glycerolmonoricinoleate 1.18 Dioctyl azelate 3.12 Ferric acetylacetonate 0.04Phenyl betanaphthylaminc 0.20 Lecithin 0.21 Copper chromite 0.50 Durenediisocyanate l .62

The following two examples represent preferred formulations for thepropellants of my invention.

EXAMPLE XIII EXAMPLE XIV INGREDIENT WEIGHT PERCENT Ammonium Perchlorate81.50 Powdered Aluminum 1.00 Aluminum Staple (0.5X4.0 62 mil) 4.00Copper Chromite 1.50 Isodccyl Pelargonate 5.00 SuccinicAnhydride-Diethanol Amine Adduet 0.12 Carboxy terminated polybutadiene6.49 (M.W.=6000) Bis( l ,Z-Propylenc)lsosebacamide 0.19 Tris(1-Aziridiny1)Phosphine Oxide 0.20

It will be understood that various modifications may be made in thisinvention without departing from the spirit thereof or the scope of theappended claims.

I claim:

1. A solid propellant composition which comprises a cured intimatemixture or a non-metallic oxidizing salt, a resin binder, and as aburning rate additive, elongated metallic staples having a heatconductivity of from about 0.10 to about 1.05 gram-cal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C, and in an amounteffective to increase the burning rate up to an amount not greater thanthat equivalent to about 15 percent by weight of the propellantcomposition.

2. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder which is thereaction product of a carboxy-terminated polydiolefin polymer and animine curing agent, and as a burning rate additive, elongated metallicstaples having a heat conductivity of from about 0.10 to about 1.05gramcal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C, in anamount effective to increase the burning rate up to an amount notgreater than that equivalent to about 15 percent by weight of thepropellant composition.

3. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a polyurethane resin binder,and as a burning rate additive, elongated metallic staples having a heatconductivity of from about 0.10 to about 1.05gramcal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C, in anamount effective to increase the burning rate up to an amount notgreater than that equivalent to about 15 percent by weight of thepropellant composition.

4. A solid propellant composition which comprises a cured intimatemixture of a solid non-metallic oxidizing salt and a cross-linked resinbinder which comprises the reaction product of a compound having, as itssole reacting groups, not less than two active hydrogen groups capableof polymerizing with an isocyanate as determined by the Zerewitinoffmethod, and a compound having, as its sole reacting groups, not lessthan two groups capable of undergoing a urethane-type reaction withhydroxy groups and as a burning rate additive, elongated metallicstaples having a heat conductivity of from about 0.10 to about 1.05gramcal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C, in anamount effective to increase the burning rate up to an amount notgreater than that equivalent to about fifteen percent by weight of thepropellant composition. I

5. A solid propellant composition which comprises a cured intimatemixture of elongated aluminum staples, a solid non-metallic oxidizingsalt, and a resin binder which comprises the reaction product of anaromatic diisocyanate, a polyether having a molecular weight betweenabout 400 and 10,000 and a trihydroxy crosslinker compound; the aluminumstaple being present in an amount effective to increase the burning rateup to an amount not greater than about 15 percent by weight, the resinbinder being present in an amount between about 5 and about 55 percentby weight, and the solid non-metallic oxidizing salt being present in anamount between about and about 45 percent by weight, all percentagesbeing given on a total propellant weight basis.

6. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder, and as aburning rate additive, elongated metallic staples of circularcross-section having a heat conductivity of from about 0.10 to about1.05 gramcal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C, adiameter of from about 2.0 to about 10 mils and a length of from 50 toabout 500 mils, and in an amount effective to increase the burning rateup to an amount not greater than that equivalent to about 15 percent byweight of the propellant composition.

7. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder which is thereaction product of a carboxy-terminated polydiolefin polymer and animine curing agent, and as a burning rate additive, elongated metallicstaples of circular cross-section, having a heat conductivity of fromabout 0.10 to about 1.05 gramcal/(sec) (sq.cm.)(C/cm) and a meltingpoint above about 600C, a diameter of from about 2.0 to about 10 milsand a length of from 50 to about 500 mils, in an amount effective toincrease the burning rate up to an amount not greater than thatequivalent to about l percent by weight of the propellant composition.

8. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a polyurethane resin binder,and as a burning rate additive, elongated metallic staples of circularcrosssection, having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C,in an amount effective to increase the burning rate up to an amount notgreater than that equivalent to about l5 percent by weight of thepropellant composition.

9. A solid propellant composition which comprises a cured intimatemixture of a solid non-metallic oxidizing salt and a cross-linkedresinbinder which comprises the reaction product of a compound having,as its sole reacting groups, not less than two active hydrogen groupscapable of polymerizing with an isocyanate as determined by theZerewitinoff method, and a compound having, as its sole reacting groups,not less than two groups capable of undergoing a urethane-type reactionwith hydroxy groups and as a burning rate additive, elongated metallicstaples of circular cross-section, having a heat conductivity of fromabout 0.10 to about 1.05 gram-cal/(sec)(sq.cm.)(C/cm) and a meltingpoint above about 600C, a diameter of from about 2.0 to about mils and alength of from 50 to about 500 mils, in an amount effectiveto increasethe burning rate up to an amount not greater than that equivalent toabout l5 percent by weight of the propellantcomposition.

10. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder, and as aburning rate additive, elongated metallic staples of rectangularcross-section having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(C/cm) and a melting point above about 600C,measure from 0.4 to about 5.0 mils on the short side, from about 1.0 toabout 20 mils on the long side and are from about 50 to about 500 milsin length, and in an amount effective to increase the burning rate up toan amount not greater than that equivalent to about percent by weight ofthe propellant composition.

11. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder which is thereaction product of a carboxy-terminated polydiolefin polymer and animine curing agent, and as a burning rate additive, elongated metallicstaples of rectangular cross-section having a heat conductivity of fromabout 0.10 to about 1.05 gram-cal/(sec) (sq.cm.)(C/cm) and a meltingpoint above about 600C, measure from 0.4 to about 5.0 mils on the shortside, from about 1.0 to about mils on the long side and are from about50 to about 500 mils in length, in an amount effective to increase theburning rate up to an amount not greater than that equivalent to about15 percent by weight of the propellant composition.

12. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a polyurethane resin binder,and as a burning rate additive, elongated metallic staples ofrectangular cross-section having a heat conductivity of from about 0.10to about 1.05 gram-cal/(sec)(sq.cm.)(C/cm) and a melting point aboveabout 600C, measure from 0.4

to about 5.0 mils on the short-side, from about 1.0 to

about 20 mils on the long side and are from about 50 to about 500 milsin length, in an amount effective to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.

13. A solid propellant composition which comprises a cured intimatemixture of a solid non-metallic oxidizing salt and a cross-linked resinbinder which comprises the reaction product of a compound having, as itssole reacting groups, not less than two active hydrogen groups capableof polymerizing with an isocyanate as determined by the Zerewitinoffmethod, and a compound having, as its sole reacting groups, not lessthan two groups capable of undergoing a urethane-type reaction withhydroxy groups and as a burning rate additive, elongated metallicstaples of rectangular crosssection having a heat conductivity of fromabout 0.10 to about 1.05 gram-cal/(sec)(sq.cm.) (C/cm) and a meltingpoint above about 600C measure from 0.4 to about 5.0 mils on the shortside, from about 1.0 to about 20 mils. on the long side and are fromabout 50 to about 500 mils in length in an amount effective to increasethe burning rate up to an amount not greater than that equivalent toabout 15 percent by weight of the propellant composition.

14. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder, and as aburning rate additive, elongated metallic staples having a heatconductivity of from about 0.10 to about 1.05gramcal/(sec)(seq.cm.)(C/cm.), a melting point above about 600C, saidelongated metallic staples being coated with a pyrotechnic mixtureselected from the group consisting of a mixture of iron and potassiumpermanganate, and a mixture of aluminum and potassium perchlorate, saidstaples being present in an amount effective to increase the burningrate up to an amount not greater than that equivalent to about 15percent by weight of the propellant composition.

15. A solid propellant composition which comprises a cured intimatemixture of a solid non-metallic oxidizing salt and a cross-linked resinbinder which comprises the reaction product of a compound having, as itssole reacting groups, not less than two active hydrogen groups capableof polymerizing with an isocyanate as determined by the Zerewitinoffmethod, and a compound having as its sole reacting groups, not less thantwo groups capable of undergoing a urethane-type reaction with hydroxygroups, and as a burning rate additive, elongated metallic stapleshaving a heat conductivity of from about 0.10 to about 1.05gramcal/(sec)(seq.cm.)(C/cm.), a melting point above about 600C, .saidelongated metallic staples being coated with a pyrotechnic mixtureselected from the .group consisting of a mixture of iron and potassiumpermanganate, and a mixture of aluminum and potassium perchlorate, saidstaples being present in an amount effective to increase the burningrate up to an amount not greater than that equivalent to about 15percent by weight of the propellant composition.

16. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin-binder which is thereaction product of a carboxy-terminated polydiolefin polymer and animine curing agent, and as a burning rate additive, elongated metallicstaples of circular cross-section, having a heat conductivity of fromabout 0.10 to about 1.05 gramcal/(sec)(sq.cm.)(C/cm.), and a meltingpoint above about 600C, 21 diameter from about 2.0 to about mils and alength of from about 50 to about 500 mils, said elongated metallicstaples being coated with a pyrotechnic mixture selected from the groupconsisting of a mixture of iron and potassium permanganate, and amixture of aluminum and potassium perchlorate, said staples beingpresent in an effective amount to increase the burning rate up to anamount not greater than that equivalent to about percent by weight ofthe propellant composition.

17. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder which is thereaction product of a carboxy-terminated polydiolefin polymer and animine curing agent, and as a burning rate additive, elongated metallicstaples of rectangular cross-section having a heat conductivity of from0.10 to about 1.05 gramcal/(sec)(seq.cm.)(C/cm.), and a melting pointabove about 600C, measuring from about 0.4 to about 5.0 mils on theshort side, from about 1.0 to about 20 mils on the long side and fromabout 50 to about 500 mils in length, said elongated metallic staplesbeing coated with a pyrotechnic mixture selected from the groupconsisting of a mixture of iron and potassium permanganate, and amixture of aluminum and potassium perchlorate, said staples beingpresent in an effective amount to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.

1. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder, and as aburning rate additive, elongated metallic staples having a heatconductivity of from about 0.10 to about 1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point above about 600*C, and in an amounteffective to increase the burning rate up to an amount not greater thanthat equivalent to about 15 percent by weight of the propellantcomposition.
 2. A solid propellant composition which comprises a curedintimate mixture of a non-metallic oxidizing salt, a resin binder whichis the reaction product of a carboxy-terminated polydiolefin polymer andan imine curing agent, and as a burning rate additive, elongatedmetallic staples having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point above about600*C, in an amount effective to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.
 3. A solid propellant composition whichcomprises a cured intimate mixture of a non-metallic oxidizing salt, apolyurethane resin binder, and as a burning rate additive, elongatedmetallic staples having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point above about600*C, in an amount effective to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.
 4. A SOLID PROPELLANT COMPOSITION WHICHCOMPRISES A CURED INTIMATE MIXTURE OF A SOLID NON-METALLIC OXIDIZINGSALT AND A CEOSS-LINKED RESIIN BINDER WHICH COMPRISES THE REACTIONPRODUCT OF A COMPOUND HAVING, AS ITS SOLE RECTING GROUPS, NOT LESS THANTWO ACTIVE HYDROGEN GROUPS CAPABLE OF POLYMERIZING WITH AN ISOCYANATE ASDETERMINED BY THE ZEREWITINOFF METHOD, AND A COMPOUND HAVING, AS ITSSOLE REACTING GROUPS, NOT LESS THAN TWO GROUPS CAPABLE OF UNDERGOING AURETHANE-TYPE REACTION WITH HYDROXY GROUPS AND AS A BURNING RATEADDITIVE, ELONGATED METALLIC STAPLES HAVING A HEAT CONDUCTIVELY OF FROMABOUT 0.10 TO ABOUT 1.05 GRAM-CAL (SEC) (SQ.CM.) (*C CM) AND A MELTINGPOINT ABOVE ABOUT 600*C, IN AN AMOUNT EFFECTIVE TO INCREASE THE BURNINGRATE UP TO AN AMOUNT NOT GREATER THAN THE EQUIVALENT TO ABOUT 15 PERCENTBY WEIGHT OF THE PROPELLANT COMPOSITION.
 5. A solid propellantcomposition which comprises a cured intimate mixture of elongatedaluminum staples, a solid non-metallic oxidizing salt, and a resinbinder which comprises the reaction product of an aromatic diisocyanate,a polyether having a molecular weight between about 400 and 10,000 and atrihydroxy cross-linker compound; the aluminum staple being present inan amount effective to increase the burning rate up to an aMount notgreater than about 15 percent by weight, the resin binder being presentin an amount between about 5 and about 55 percent by weight, and thesolid non-metallic oxidizing salt being present in an amount betweenabout 95 and about 45 percent by weight, all percentages being given ona total propellant weight basis.
 6. A solid propellant composition whichcomprises a cured intimate mixture of a non-metallic oxidizing salt, aresin binder, and as a burning rate additive, elongated metallic staplesof circular cross-section having a heat conductivity of from about 0.10to about 1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point aboveabout 600*C, a diameter of from about 2.0 to about 10 mils and a lengthof from 50 to about 500 mils, and in an amount effective to increase theburning rate up to an amount not greater than that equivalent to about15 percent by weight of the propellant composition.
 7. A solidpropellant composition which comprises a cured intimate mixture of anon-metallic oxidizing salt, a resin binder which is the reactionproduct of a carboxy-terminated polydiolefin polymer and an imine curingagent, and as a burning rate additive, elongated metallic staples ofcircular cross-section, having a heat conductivity of from about 0.10 toabout 1.05 gram-cal/(sec) (sq.cm.)(*C/cm) and a melting point aboveabout 600*C, a diameter of from about 2.0 to about 10 mils and a lengthof from 50 to about 500 mils, in an amount effective to increase theburning rate up to an amount not greater than that equivalent to about15 percent by weight of the propellant composition.
 8. A solidpropellant composition which comprises a cured intimate mixture of anon-metallic oxidizing salt, a polyurethane resin binder, and as aburning rate additive, elongated metallic staples of circularcross-section, having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point above about600*C, in an amount effective to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.
 9. A solid propellant composition whichcomprises a cured intimate mixture of a solid non-metallic oxidizingsalt and a cross-linked resin binder which comprises the reactionproduct of a compound having, as its sole reacting groups, not less thantwo active hydrogen groups capable of polymerizing with an isocyanate asdetermined by the Zerewitinoff method, and a compound having, as itssole reacting groups, not less than two groups capable of undergoing aurethane-type reaction with hydroxy groups and as a burning rateadditive, elongated metallic staples of circular cross-section, having aheat conductivity of from about 0.10 to about 1.05gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point above about 600*C, adiameter of from about 2.0 to about 10 mils and a length of from 50 toabout 500 mils, in an amount effective to increase the burning rate upto an amount not greater than that equivalent to about 15 percent byweight of the propellant composition.
 10. A solid propellant compositionwhich comprises a cured intimate mixture of a non-metallic oxidizingsalt, a resin binder, and as a burning rate additive, elongated metallicstaples of rectangular cross-section having a heat conductivity of fromabout 0.10 to about 1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a meltingpoint above about 600*C, measure from 0.4 to about 5.0 mils on the shortside, from about 1.0 to about 20 mils on the long side and are fromabout 50 to about 500 mils in length, and in an amount effective toincrease the burning rate up to an amount not greater than thatequivalent to about 15 percent by weIght of the propellant composition.11. A solid propellant composition which comprises a cured intimatemixture of a non-metallic oxidizing salt, a resin binder which is thereaction product of a carboxy-terminated polydiolefin polymer and animine curing agent, and as a burning rate additive, elongated metallicstaples of rectangular cross-section having a heat conductivity of fromabout 0.10 to about 1.05 gram-cal/(sec) (sq.cm.)(*C/cm) and a meltingpoint above about 600*C, measure from 0.4 to about 5.0 mils on the shortside, from about 1.0 to about 20 mils on the long side and are fromabout 50 to about 500 mils in length, in an amount effective to increasethe burning rate up to an amount not greater than that equivalent toabout 15 percent by weight of the propellant composition.
 12. A solidpropellant composition which comprises a cured intimate mixture of anon-metallic oxidizing salt, a polyurethane resin binder, and as aburning rate additive, elongated metallic staples of rectangularcross-section having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(*C/cm) and a melting point above about600*C, measure from 0.4 to about 5.0 mils on the short side, from about1.0 to about 20 mils on the long side and are from about 50 to about 500mils in length, in an amount effective to increase the burning rate upto an amount not greater than that equivalent to about 15 percent byweight of the propellant composition.
 13. A solid propellant compositionwhich comprises a cured intimate mixture of a solid non-metallicoxidizing salt and a cross-linked resin binder which comprises thereaction product of a compound having, as its sole reacting groups, notless than two active hydrogen groups capable of polymerizing with anisocyanate as determined by the Zerewitinoff method, and a compoundhaving, as its sole reacting groups, not less than two groups capable ofundergoing a urethane-type reaction with hydroxy groups and as a burningrate additive, elongated metallic staples of rectangular cross-sectionhaving a heat conductivity of from about 0.10 to about 1.05gram-cal/(sec)(sq.cm.) (*C/cm) and a melting point above about 600*Cmeasure from 0.4 to about 5.0 mils on the short side, from about 1.0 toabout 20 mils on the long side and are from about 50 to about 500 milsin length in an amount effective to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.
 14. A solid propellant composition whichcomprises a cured intimate mixture of a non-metallic oxidizing salt, aresin binder, and as a burning rate additive, elongated metallic stapleshaving a heat conductivity of from about 0.10 to about 1.05gram-cal/(sec)(seq.cm.)(*C/cm.), a melting point above about 600*C, saidelongated metallic staples being coated with a pyrotechnic mixtureselected from the group consisting of a mixture of iron and potassiumpermanganate, and a mixture of aluminum and potassium perchlorate, saidstaples being present in an amount effective to increase the burningrate up to an amount not greater than that equivalent to about 15percent by weight of the propellant composition.
 15. A solid propellantcomposition which comprises a cured intimate mixture of a solidnon-metallic oxidizing salt and a cross-linked resin binder whichcomprises the reaction product of a compound having, as its solereacting groups, not less than two active hydrogen groups capable ofpolymerizing with an isocyanate as determined by the Zerewitinoffmethod, and a compound having as its sole reacting groups, not less thantwo groups capable of undergoing a urethane-type reaction with hydroxygroups, and as a burning rate additive, elongated metallic stapleshavinG a heat conductivity of from about 0.10 to about 1.05gram-cal/(sec)(seq.cm.)(*C/cm.), a melting point above about 600*C, saidelongated metallic staples being coated with a pyrotechnic mixtureselected from the group consisting of a mixture of iron and potassiumpermanganate, and a mixture of aluminum and potassium perchlorate, saidstaples being present in an amount effective to increase the burningrate up to an amount not greater than that equivalent to about 15percent by weight of the propellant composition.
 16. A solid propellantcomposition which comprises a cured intimate mixture of a non-metallicoxidizing salt, a resin-binder which is the reaction product of acarboxy-terminated polydiolefin polymer and an imine curing agent, andas a burning rate additive, elongated metallic staples of circularcross-section, having a heat conductivity of from about 0.10 to about1.05 gram-cal/(sec)(sq.cm.)(*C/cm.), and a melting point above about600*C, a diameter from about 2.0 to about 10 mils and a length of fromabout 50 to about 500 mils, said elongated metallic staples being coatedwith a pyrotechnic mixture selected from the group consisting of amixture of iron and potassium permanganate, and a mixture of aluminumand potassium perchlorate, said staples being present in an effectiveamount to increase the burning rate up to an amount not greater thanthat equivalent to about 15 percent by weight of the propellantcomposition.
 17. A solid propellant composition which comprises a curedintimate mixture of a non-metallic oxidizing salt, a resin binder whichis the reaction product of a carboxy-terminated polydiolefin polymer andan imine curing agent, and as a burning rate additive, elongatedmetallic staples of rectangular cross-section having a heat conductivityof from 0.10 to about 1.05 gram-cal/(sec)(seq.cm.)(*C/cm.), and amelting point above about 600*C, measuring from about 0.4 to about 5.0mils on the short side, from about 1.0 to about 20 mils on the long sideand from about 50 to about 500 mils in length, said elongated metallicstaples being coated with a pyrotechnic mixture selected from the groupconsisting of a mixture of iron and potassium permanganate, and amixture of aluminum and potassium perchlorate, said staples beingpresent in an effective amount to increase the burning rate up to anamount not greater than that equivalent to about 15 percent by weight ofthe propellant composition.